This invention relates to the field of living specimen bone biopsy and to the trephine sampling of bone.
Trabecular bone found in the axial skeleton of animal and human test subjects is especially responsive to conditions of weightlessness, decreased usage, and physical exercise in anthropoid test subjects. Such bone is also of special interest in the diagnosis and treatment of certain disease processes. Since bone is living tissue and is being continuously remodeled throughout the life of a living specimen, changes in bone usage or loading are, for example, followed by confirming structural remodeling of the loaded bone wherein the remodeling follows the direction and functional stress applied by the loading. According to a generally accepted theory proposed by J. D. Wolff in Das Gesets der Transformation der Knochen, Berlin, A. Hirschwald, 1892, pp. 1-152, when the stresses applied to a weight-bearing living skeleton are changed or removed, such as through immobilization or gravity changes, directly responsive structural change or bone remodeling is expected. Since little is known of the physiology of bone remodeling under conditions of weightlessness and related mechanical stresses, the continued participation of human and animal test subjects in space efforts suggest a need for improved arrangements for studying bone remodeling.
The study and treatment of disease processes including the effects of bone tuberculosis, metabolic osteoporosis, disuse osteoporosis, (e.g., from prolonged bed confinement), syphilis, paraplegia, cast confinement, and other causes, serve also as a stimulus for continued study of bone remodeling and especially to bone degeneration processes.
Radiology, radiographic densitometry, and photon absorption spectrometry have been previously used in the analysis of bone with limited degrees of success--in view of the absence of quantitative information from such procedures. In sharp contrast of this limitation, however, a variety of reliable and accurate analytical techniques such as scanning electron microscopy, transmission electron microscopy, histomorphometry, after serial bone labeling, histochemistry, biochemistry, and mechanical strength tests are available for use in analyzing actual bone samples from a test subject.
The present invention provides an arrangement for obtaining desirable bone tissue samples from living animal or human test subjects which is both humane in that it is non-disabling and productive of only minimal and short duration discomfort for the test subject, and is also cost-efficient in permitting continued and repeated use of a single test subject for both prolonged and multiple studies.
Major additional considerations in obtaining axial skeleton bone biopsy samples include the location of the biopsy site, bones in the leg, for example, having heretofore been popular for such samples; and the obtaining of a sufficient quantity of undamaged specimen from an area representative of the conditions being studied. Trabecular bone, i.e., lattice organized crystalline bone, develops along the lines of greatest stress in the skeleton of an anthropoid and comprises the major weight bearing structural element in such organisms. A vertebral biopsy, especially a biopsy of the vertebral centrum portion has been found especially desirable for trabecular bone study in the case of anthropoids such as the rhesus monkey (macaca mulatta). Sampling accomplished in the easily accessible and structurally active spinal lumbar area of such test specimens is found to be particularly indicative of bone remodeling and other bone conditions.
The patent art includes several examples of bone sampling, skeletal measuring, and related procedures, this art includes the patent of R. H. Romney, U.S. Pat. No. 3,374,548, which described a stereotaxic system useful in tracing or following a pre-existing contour map in locating a drill bit precisely with respect to the skull of a test subject. The Romney apparatus includes a plurality of linear and angular adjustments capable of locating the drill bit or other cutting tool in most positions around the rigidily held skull of an anesthesized animal test subject. In the Romney apparatus the test subject is positioned on a stage 12 while a mensurative standard or map 45 is provided for use in locating and recording the positions of the drilling unit or an electrode about the skull of the test subject.
Other skull positioning instruments are shown in the patents of Z. R. Mocarski, U.S. Pat. No. 3,073,310, and H. Hainult, U.S. Pat. No. 3,508,552, and provide skull access for x-ray photograph and surgical purposes, respectively.
Positioning apparatus for other portions of the human anatomy are shown in the patents of M. F. O'Connor, U.S. Pat. No. 1,571,140, and G. R. Marshall, U.S. Pat. No. 2,245,350, which concern a chiropractic locating device and a lower spinal area hypodermic needle anesthetic administering apparatus, respectively.
While the above-identified patents indicate the use of mechanical aids in locating precise positions about a test subject to have been practiced for some time, none of these prior patents teach the use of a simple, reliable device for achieving fast, safe spinal vertebra trephine biopsy samples.